Effect of melatonin on ketamine-induced apoptosis in hippocampal neurons of fetal rats

Abstract

Objective To investigate the effect of melatonin on ketamine-induced apoptosis in hippocampal neurons of fetal rats.Methods Sixteen to eighteen day pregnant Sprague Dawley rats were anesthetized.The fetal rats were obtained under sterile condition and decapitated.The hippocampal neurons were isolated and primary cultured for 5 days.The primary cultured neurons were randomly divided into 5 groups (n =6 each):control group (group C),ketamine group (group K),and 1.0,2.5 and 5.0 mmol/L melatonin groups (groups M1-3 respectively).Ketamine with the final concentration of 1 000 μmol/L was added to the culture medium and the neurons were incubated for 3 h in group K.In groups M1-3,1.0,2.5 and 5.0 mmol/L melatonin were added to the culture medium,respectively,at 60 min before the addition of ketamine,and the neurons were incubated for 3 h.While the equal volume of normal saline was added instead in group C.The neuronal viability during the developmental phase was assessed by MTT assay.The mitochondrial membrane potential (Ψm) was measured by flow cytometry.The expression of cAMP response element binding protein phosphorylation (p-CREB (Ser133)),Bcl-2,Bax,and cytochrome C was detected by Western blot.Results Compared with group C,the neuronal viability and Ψm were significantly decreased,and the expression of p-CREB and Bcl-2 was down-regulated,while the expression of Bax and cytochrome C was up-regulated in group K (P ＜ 0.05).Compared with group K,Ψm was significantly increased in groups M2 and M3,and the neuronal viability was significantly increased,the expression of Bcl-2 was up-regulated,while the expression of Bax and cytochrome C was down-regulated in groups M1-3 (P ＜ 0.05).Conclusion Melatonin can protect the hippocampal neurons of fetal rats from apoptosis triggered by ketamine via regulating the expression of Bcl-2 and Bax,stabilizing Ψm,inhibiting the release of cytochrome C from mitoehondria,and preventing apoptosome formation. Key words: Melatonin; Ketamine; Membrane potential, mitochondrial; Hippocampus; Neurons; Apoptosis